Process for Removing Nickel and Vanadium From Hydrocarbons

ABSTRACT

Nickel and/or vanadium can be removed or transferred from a hydrocarbon phase to a water phase using an Extractant Composition selected from an isocyanate, a thiocyanate, a cyanides, mercaptides, nitrites, and mixtures thereof. The Extractant Composition may also include at least one mineral acid, a solvent, and other additives. The invention permits transfer of vanadium and nickel from a hydrocarbon into an aqueous phase with little or no hydrocarbon phase undercarry into the aqueous phase. The composition is particularly useful in treating crude oil.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from the U.S. Provisional PatentApplication having the Ser. No. 60/887,262; which was filed on Jan. 30,2007, the contents of which are incorporated herein by reference intheir entirety.

FIELD OF THE INVENTION

The present invention relates to a method for removing metals fromhydrocarbons. The present invention particularly relates to removingvanadium and nickel from hydrocarbons.

BACKGROUND OF THE INVENTION

For the purposes of the present application, the terms “hydrocarbon” and“hydrocarbons” mean the large class of organic compounds containingprimarily carbon and hydrogen that are produced from crude oil; fromcoal, lignite, tar sands, and the like; from recycled hydrocarbons; andfrom biological sources such as bio-diesel and the like; as well as fromother alternative energy sources.

The largest source of hydrocarbons currently used is crude oil. Crudeoil is often contaminated with contamination coming from severalsources, including, but not necessarily limited to:

Brine contamination as a result of the brine associated with the crudeoil in the ground;

Minerals, clay, silt, and sand from the formation around the oil wellbore;

Metals including calcium, zinc, silicon, nickel, sodium, vanadium,potassium, etc.;

Nitrogen-containing compounds such as amines used to scrub H₂S fromrefinery gas streams in amine units, or from amines used as neutralizersin crude unit overhead systems, and also from H₂S scavengers used in theoilfield; and

Iron sulfides and iron oxides resulting from pipeline and vesselcorrosion during production, transport, and storage.

Nickel and vanadium can be a problem when present in hydrocarbons in atleast two ways. First, both metals are toxic in humans. Ironically, bothnickel and vanadium are also nutrients, but like many nutrients, theyare toxic above a certain level or concentration. The tolerable upperintake level for vanadium is 1.8 mg of vanadium per day.

Toxicity has occurred in workers exposed to nickel dust or nickelcarbonyl formed in refining. Increased risk of nasal and lung cancerswas linked to occupational nickel exposure before current workplacesafety standards were set. Environmental sources of lower levels ofnickel include tobacco, dental or orthopedic implants, stainless-steelkitchen utensils and inexpensive jewelry.

Repeated exposures to nickel may lead to asthma and contact dermatitis,symptoms of which may worsen if the diet is high in nickel. The oraltoxic dose is about 1000 times the amount consumed in food. Differentchemical forms vary widely in toxicity. Excessive nickel in tissues ispro-oxidant (damaging chromosomes and other cell components) and altershormone and enzyme activities, movement of ions through membranes, andimmune function. These effects can change glucose tolerance, bloodpressure, response to stress, growth rate, bone development andresistance to infection. Under some conditions, large amounts of nickelmay precipitate magnesium deficiency or cause accumulation of iron orzinc.

The recommended Nickel content of Western self-selected andinstitutional diets ranges from 60 to 260 μg/day. If follows then thatlevels that are 1000 times this may be toxic and thus excess nickel maybe undesirable in hydrocarbons, especially hydrocarbons that are used toprepare foods or prepare objects that will be in contact with foods.

Another way that nickel and vanadium may be a problem is undesiredchemical reactions. For example, when crude oil is processed in arefinery, it is often put through fluidized bed reactors. Both nickeland vanadium can interact with certain catalysts, in some instancesdeactivating the catalysts. The costs associated with purchasing newcatalysts or regenerating contaminated catalysts can be very high. Lostproductivity of refinery units during the removal and replacement ofspent catalysts is also a source of such undesirable costs. It followstherefore that it would be desirable in the art of making, selling,recycling, and using hydrocarbons to be able to remove as much vanadiumand nickel as possible from the hydrocarbons. It would be particularlydesirable in the art if an extractant composition (ExtractantComposition) could be used that would facilitate the extraction orremoval of nickel and vanadium from hydrocarbons while not complicatingother processes related to the producing, selling, using and recyclingof hydrocarbons.

SUMMARY OF THE INVENTION

In one aspect, the invention is a process for removing nickel andvanadium from a hydrocarbon comprising admixing the hydrocarbon with anExtractant Composition and separating the Extractant Composition fromthe hydrocarbon.

In another aspect, the invention is a process for removing nickel andvanadium from a hydrocarbon comprising admixing the hydrocarbon with anExtractant Composition and separating the Extractant Composition fromthe hydrocarbon wherein the Extractant Composition includes water. Insome embodiment of the invention, the process may also include one ormore process steps wherein nickel and/or vanadium are isolated from theExtractant Composition.

In still another aspect, the invention is a process for removing nickeland vanadium from a hydrocarbon comprising admixing the hydrocarbon withan Extractant Composition and separating the Extractant Composition fromthe hydrocarbon wherein the Extractant Composition is selected from athe group comprising thiocyanates, isocyanates, cyanides, mercaptides,nitrites, and mixtures thereof.

In one embodiment of the invention, there is provided, in one form, amethod of transferring nickel and vanadium from a hydrocarbon phase to awater phase involving adding to an emulsion of hydrocarbon and water, aneffective amount of an Extractant Composition to transfer the nickel andvanadium from a hydrocarbon phase to a water phase. The emulsion is thenresolved into a hydrocarbon phase and an aqueous phase, wherein at leasta portion of the metals have been transferred to the aqueous phase.

In some embodiments, the invention may be practiced using at least oneadditional component that may be a hydrocarbon solvent, a corrosioninhibitor, a demulsifier, a scale inhibitor, metal chelants, wettingagents and mixtures thereof.

DETAILED DESCRIPTION OF THE INVENTION

In the practice of the invention, a hydrocarbon is admixed with anExtractant Composition. The Extractant Composition includes a componentselected from the group consisting of isocyanates, thiocyanates,cyanides, mercaptides, nitrites, and mixtures thereof. Isocyanatesuseful with the invention include, but are not limited to methylenediphenyidiisocyanate, toluene diisocyanate, and the like.

Thiocyanates useful with the invention include, but are not limited topotassium thiocyanates, sodium thiocyanates, ammonium thiocyanates, andmixtures thereof.

The process of the invention may be used with equipment that isdedicated to the process. However, in crude oil refineries and possiblyother plants that prepare, process, or recycle hydrocarbons, there is apiece of equipment that is already in place that may be used with theprocess. This apparatus is known as a “Desalting Unit” and the processis known as “desalting.”

As already stated, hydrocarbons can be and often are contaminated withbrine contamination, minerals, clay, silt, sand, calcium, zinc, silicon,nickel, sodium, vanadium, potassium, nitrogen-containing compounds suchas amines and Iron sulfides and iron oxides. At least some of thematerials are routinely removed using one or more desalting units. Suchdesalting is necessary prior to further processing to remove these saltsand other inorganic materials that would otherwise cause fouling anddeposits in downstream heat exchanger equipment and/or form corrosivesalts detrimental to crude oil processing equipment.

In the refining of crude oil, desalting is often practiced as theresolution of the natural emulsion of water that accompanies the crudeoil by creating another emulsion in which about 5 percent relative washwater is dispersed into the oil. The emulsion mix is directed into adesalter vessel containing a parallel series of electrically chargedplates. Under this arrangement, the oil and water emulsion is exposed tothe applied electrical field. An induced dipole is formed on each waterdroplet within the emulsion that causes electrostatic attraction andcoalescence of the water droplets into larger and larger droplets.Eventually, the emulsion resolves into two separate phases; the oilphase (top layer) and the water phase (bottom layer). The streams ofdesalted crude oil and effluent water are separately discharged from thedesalter.

The entire desalting process is a continuous flow procedure as opposedto a batch process. Normally, chemical additives are injected before orconcurrently with mixing to help resolve the oil/water emulsion inaddition to the use of electrostatic coalescence. These additiveseffectively allow small water droplets to more easily coalesce bylowering the oil/water interfacial tension.

Crude oil that contains a high percent of particulate solids cancomplicate the desalting process. The particulate solids, by nature,would prefer to transfer to the water phase. However, much of the solidsin a crude oil exist in tight water-in-oil emulsions. That is,oil-wetted solids in high concentration in the crude may help form tightoil and water emulsions that are difficult to resolve. These tightemulsions are often referred to as “rag” and may exist as a layerbetween the separated oil and water phases. The rag layer inside thedesalter vessel may grow to such an extent that some of it will beinadvertently discharged with the water phase. This may be a problem forthe waste water treatment plant since the rag layer still contains ahigh percentage of unresolved emulsified oil.

Much of the solids encountered during crude oil desalting consist ofiron, most commonly as particulate iron such as iron oxide, ironsulfide, etc. Other metals that are desirably removed include, but arenot necessarily limited to, calcium, zinc, silicon, nickel, sodium,potassium, and the like, and typically a number of these metals arepresent. Some of the metals may be present in a soluble form. The metalsmay be present in inorganic or organic forms. In addition tocomplicating the desalter operation, iron and other metals are ofparticular concern to further downstream processing. This includes thecoking operation since iron and other metals remaining in the processedhydrocarbon yields a lower grade of coke. Removing the metals from thecrude oil early in the hydrocarbon processing stages is desired toeventually yield high quality coke as well as to limit corrosion andfouling processing problems.

Several treatment approaches have been made to reduce total metal levelsand these all center on the removal of metals at the desalter unit.Normally, the desalter only removes water soluble inorganic salts suchas sodium or potassium chlorides. Some crude oils contain waterinsoluble metal organic acid salts such as calcium naphthenante and ironnaphthenante, which are soluble or dispersed as fine particulate matterin the oil but not in water.

In the practice of the process of the present invention, it would bedesirable to use an Extractant Composition that allows for the removalof nickel and vanadium, but does not otherwise complicate desalter orother separation device operations. For example, the ExtractantCompositions of the present invention do not cause excessive oilcarry-under in the aqueous phase within a desalter.

In the process of the present invention, the addition of an ExtractantComposition to a crude oil can significantly reduce the amount of nickeland vanadium in the hydrocarbon when it is run through a desalter in arefinery.

In one embodiment of the invention, the Extractant Composition is anaqueous additive. Being an aqueous additive, the Extractant Compositionis typically added to the wash water in the desalter. This improvesdistribution of the Extractant Composition in the oil although additionto the aqueous phase, but it should not be viewed as a requirement forthe composition of the invention to work.

It is contemplated and within the scope of the disclosure and claims ofthis application that the Extractant Compositions will be used togetherwith and/or include other components including, but not necessarilylimited to, corrosion inhibitors, demulsifiers, pH adjusters, metalchelants, scale inhibitors, hydrocarbon solvents, and mixtures thereof.Metal chelants are compounds that complex with metals to form chelates.Mineral acids may be used in some applications since metal removal maysometimes best be accomplished at an acidic pH. Suitable mineral acidsfor use with the process of this invention include, but are notnecessarily limited to, sulfuric acid, hydrochloric acid, phosphoricacid, nitric acid, phosphorous acid, and mixtures thereof.

In one embodiment of the invention, the method of this invention ispracticed in a refinery desalting process that involves washing thecrude emulsion with wash water. In one non-limiting embodiment of theinvention, the amount of mineral acid used may be sufficient to lowerthe pH of the wash water to 10 or below. In some embodiments of theinvention, it may be necessary or preferred to lower the pH of the washwater to 8 or below, alternatively to 6 or below.

It will be appreciated that the necessary, effective, or desiredproportions of the Extractant Composition will be difficult to predictin advance, since proportions or dosages may be dependent upon a numberof factors, including, but not necessarily limited to, the nature of thehydrocarbon, the concentration of nickel and/or vanadium to be removed,the temperature and pressure conditions of the process, the particularExtractant Composition and mineral acid used, etc. In general, the moremetal there is to be removed, the more of the Extractant Compositionthat must be added.

One of ordinary skill in the art of producing, using and/or recyclinghydrocarbons will be well skilled in selecting optimum level ofExtractant Composition to add. Still, generally, the extractantcompositions useful with the present invention will be used in aconcentration relative to the water used in the process of from about 30to about 10,000 ppm in one embodiment. In another embodiment, they willbe used at a concentration of from about 75 to about 5000 ppm. In stillanother embodiment, they will be used at a concentration of from about100 to 1000 ppm.

When practiced in a desalter, the Extractant Composition of thisinvention is injected into the wash water before the mix valve in neatform or diluted with water, alcohol or similar solvent suitable to keepall additive components in solution. The amount of solvent used mayrange from about 10 to about 95 wt. %, based on the total composition,preferably from about 50 to about 10 wt. %.

The concentration of the Extractant Composition of this invention to beused in a hydrocarbon, such as crude oil, to be effective is verydifficult to predict in advance since it depends on multiple,interrelated factors including, but not limited to, the composition ofthe crude, the desalting conditions (temperature, pressure, etc.), theflow rate of the crude and its residence time in the desalter, amongothers. Nevertheless, for the purposes of non-limiting illustration, theproportion of the Extractant Composition that may be used in thehydrocarbon (not including any solvent or mineral acid) may range fromabout 1 to about 8000 ppm-w, more preferably from about 10 to about 1000ppm-w and will depend on the concentration of metal species to beremoved. While the process of the invention may be used to remove 90greater percent (substantially all) of the nickel and vanadium present,for economic reasons a refinery or other practitioner may chose to leavesome of the metals in the hydrocarbon at an acceptably low level ofcontamination. In those cases the treatment level can be correspondinglyreduced.

It is most preferred, of course, that in the practice of this inventionthere be no oil carryunder in the aqueous phase, or that oil carry-underis at least minimized. Further, while it is preferred that all of thenickel and/or vanadium transfers to the aqueous phase, in onenon-limiting theory of the invention, some of the metals may betransferred from the oil phase into the rag. This proportion of metalsand/or amines is then removed when the rag is cleaned out.

It is preferred, of course, in most embodiments of the invention, thatin the practice of this invention, all of the nickel and vanadiumtransfer from a hydrocarbon to an aqueous phase. In another non-limitingembodiment of the invention, 90 percent or less of the vanadium andnickel are removed. In still another embodiment, 50 percent or even 20%or less of the nickel and vanadium are removed. In some cases therefinery may chose to leave higher percentages of the metals in ahydrocarbon if the detrimental effects are judged to be economicallyacceptable.

While a desalter in an oil refinery can be a desirable location in whichto practice the method of the invention, any apparatus that allows forthe admixing of an Extractant Composition with a hydrocarbon followed byresolving the hydrocarbon and Extractant Composition admixture into ahydrocarbon stream and an aqueous stream may be used. For example, adedicated wash vessel can be used to extract nickel and vanadium fromhydrocarbons.

In a dedicated vessel, the Extractant Composition is admixed with ahydrocarbon. In one embodiment, the Extractant Composition is admixedfirst with the hydrocarbon and then the hydrocarbon and ExtractantComposition is then admixed with water to form an emulsion and thenresolved into a hydrocarbon phase and an aqueous phase. The ExtractantComposition and at least some of the nickel and vanadium present in thehydrocarbon, are then present in the aqueous phase.

In another embodiment, the Extractant Composition is present in thewater prior to admixing the water with the hydrocarbon. Embodimentswhere the Extractant Composition is present in both the water and thehydrocarbon, as well as where the Extractant Composition is essentiallya third feed component are also within the scope of the invention. Inany of these embodiments, other additives and processes may be used toassist in first forming an emulsion and then in resolving the emulsioninto an aqueous phase and a hydrocarbon phase.

In one embodiment of the invention, the nickel and vanadium removed froma hydrocarbon may be recovered for use or sale. These metals may berecovered from the aqueous solution by any suitable technique. Exemplarytechniques include, but are not limited to, resin adsorption methodssuch as resin-in-pulp, resin-in-solution, and resin-in-leach; solventextraction; cementation; electrolysis; precipitation; and/orcombinations of two or more of these techniques.

The invention will be illustrated further with reference to thefollowing Examples, which are not intended to limit the invention, butinstead illuminate it further.

The following Electrostatic Desalting Dehydration Apparatus (EDDA) TestMethod was employed to evaluate compounds as Extractant Compositions.The EDDA is a laboratory test device to simulate the desalting process.

EDDA Test Method

-   1. Add 800, 600 or 400 ml of crude oil to be tested minus the    percent of wash water (depending on the number of tubes the EDDA    will hold) to a Waring blender.-   2. Add the required percentage of wash water to the blender to bring    the total volume up to 800, 600 or 400 ml.-   3. Mix at 50% speed (on the Variac) for 30 seconds. The speed can be    reduced if the ΔP on the mix valve is low.-   4. Pour the mixture into the EDDA tubes to just below the 100 ml    line.-   5. Place the tubes in the EDDA heating block that is at the desired    test temperature (99° C.).-   6. Add the desired quantity of demulsifier, in ppm, to each tube.    With every test, a blank must be run for comparison purposes.-   7. Place the screw top electrode in the tubes and allow the samples    to heat for approximately 15 minutes.-   8. Tighten the caps and shake each tube 100-200 times and place back    in the heating block to reheat for five minutes.-   9. Place the electrode cover over the tubes and lock into place.    Make sure that there is good contact between the cover and the    electrode caps.-   10. Set the time for five minutes and run at 1500-3000 volts,    depending on the test requirements.-   11. At the end of the five minutes, pull the tubes out and check for    the percent water drop. Also check the quality of the interface and    the quality of the water and record it.-   12. Repeat steps 9, 10, and 11 until the desired total residence    time is achieved.-   13. Determine the best candidates and run a dehydration test on    those samples.    -   a) Fill the desired number of 12.5 ml centrifuge tubes to the        50% mark with xylene.    -   b) Use a glass syringe to pull 5.8 ml of dehydrated crude sample        from the desired level in the tube and mix in with the xylene in        the centrifuge tubes.    -   c) Centrifuge the tubes at 2000 rpm for 4 minutes.    -   d) Check for the quantity of water, emulsion, and solids that        are present in the bottom of the tube and record.

EXAMPLE

An EDDA test, as set forth above, is conducted using North African CrudeOil as the hydrocarbon and with the wash water level in Step 2 being 5%.The Extractant Composition is incorporated into the wash water at theconcentrations shown in the Table. The test is conducted using a blankas a control and the materials shown in the Table as ExtractantCompositions.

After completing the EDDA test, the EDDA desalted hydrocarbon is testedfor nickel and vanadium. Test results are shown below in the Table.

TABLE Extractant Composition Percent Concentration [V] [Ni] ReductionExtractant Composition (ppm) ppm ppm V/Ni Blank na 16.8 36.6 na TolueneDiisocyanate 100 11.1 27.7 34/24 Potassium Thiocyanate 165 10.0 25.641/30 Mercaptoacetic Acid* 100 15.5 34.4 7/6 Dithiocarbamate A* 100 15.634.2 7/6 Dithiocarbamate B* 100 16.8 36.2 0/1 Phosphonium Sulfate* 20015.2 36.6 na *A comparative example and not an example of the invention.

The results shown above in the Table demonstrate that the toluenediisocyanate and potassium thiocyanate, when used as the ExtractantComposition of the invention, are effective in causing a substantialreduction in the concentration of vanadium and nickel in North AmericanCrude Oil samples.

1. A process for removing nickel and vanadium from a nickel and/orvanadium containing hydrocarbon (Hydrocarbon) comprising admixing theHydrocarbon with an Extractant Composition and separating the ExtractantComposition from the Hydrocarbon wherein some or substantially all ofthe nickel and/or vanadium is transferred from the Hydrocarbon to theExtractant Composition.
 2. The process of claim 1 wherein ExtractantComposition includes a compound selected from the group consisting ofthiocyanates, isocyanates, cyanides, mercaptides, nitrites, and mixturesthereof.
 3. The process of claim 2 wherein the Extractant Compositionincludes an isocyanate or a thiocyanate.
 4. The process of claim 3wherein the Extractant Composition includes toluene diisocyanate.
 5. Theprocess of claim 3 wherein the Extractant Composition includes potassiumthiocyanate.
 6. The process of claim 1 wherein the ExtractantComposition includes water.
 7. The process of claim 1 additionallycomprising admixing with the Hydrocarbon at least one additionalcomponent selected from the group consisting of a hydrocarbon solvent, acorrosion inhibitor, a demulsifier, a scale inhibitor, metal chelants,wetting agents and mixtures thereof.
 8. The process of claim 1 whereinthe Hydrocarbon is in the form of a water and Hydrocarbon emulsion. 9.The process of claim 1 wherein the Hydrocarbon and ExtractantComposition are admixed to form an emulsion.
 10. The process of claim 1wherein the Hydrocarbon and the Extractant Composition are separatedusing a Desalting Unit.
 11. The process of claim 6 wherein theExtractant Composition includes a compound selected from the groupconsisting of thiocyanates, isocyanates, cyanides, mercaptides,nitrites, and mixtures thereof; at a weight concentration of from about30 to 10000 ppm.
 12. The process of claim 11 wherein the ExtractComposition includes a compound selected from the group consisting ofthiocyanates, isocyanates, cyanides, mercaptides, nitrites, and mixturesthereof; at a weight concentration of from about 75 to 5000 ppm.
 13. Theprocess of claim 12 wherein the Extract Composition includes a compoundselected from the group consisting of thiocyanates, isocyanates,cyanides, mercaptides, nitrites, and mixtures thereof; at a weightconcentration of from about 100 to 1000 ppm.
 14. The process of claim 9wherein the Extractant Composition is admixed neat with the Hydrocarbonand water emulsion.
 15. The process of claim 9 wherein the ExtractantComposition is admixed with the Hydrocarbon and water emulsion andwherein the Extract Composition includes a compound selected from thegroup consisting of thiocyanates, isocyanates, cyanides, mercaptides,nitrites, and mixtures thereof; dissolved in a solvent.
 16. The processof claim 15 wherein a solvent is present in the Extractant Compositionat a concentration of from about 10 percent to about 95 percent.
 17. Theprocess of claim 1 wherein the process is performed at a pH of less thanor equal to about
 10. 18. The process of claim 17 wherein the pH ofwater associated with the Hydrocarbon and/or the Extractant Compositionis adjusted using a mineral acid.
 19. A process for removing nickel andvanadium from a nickel and/or vanadium containing hydrocarbon(Hydrocarbon) comprising admixing the Hydrocarbon with an ExtractantComposition and separating the Extractant Composition from theHydrocarbon wherein some or substantially all of the nickel and/orvanadium is transferred from the Hydrocarbon to the ExtractantComposition and further comprising isolating the nickel and/or vanadiumfrom the Extractant Composition.
 20. The process of claim 19 wherein thenickel and/or vanadium isolated from the Extractant Composition isrecycled.